Field of the Invention
The present invention relates to an optical element shaping mold set for shaping an optical element and an optical element manufacturing method by which an optical element is manufactured.
Description of the Related Art
As a conventional method of manufacturing an optical element, a method is known in which a mold set having an upper mold, a lower mold and a tubular sleeve set around the upper and lower molds is used so as to heat, press and cool the shaping-target material.
Regarding the above optical element manufacturing method, a technique of having a linear expansion coefficient of the outer peripheral mold that is smaller than the linear expansion coefficient of the inner peripheral mold so as to control the position of the inner peripheral mold by utilizing the thermal expansion difference is known as a technique for increasing the decentering accuracy of an optical element (for example Japanese Laid-open Patent Publication No. 2008-189517 and Japanese Laid-open Patent Publication No. 2006-151788).
Further, a technique in which a slit is provided to a sleeve is known although this technique is for pressing the outer peripheral mold onto the inner peripheral mold.